Apparatus for ship stabilization



' y 1969 P. H. TANNER 3,442,243

APPARATUS FOR SHIP STABILIZATION Filed Jan. 15, 1968 Sheet of 4 May 6,1969 Filed Jan. 15, 1968 P. H. TANNER APPARATUS FOR SHIP STABILIZATIONSheet 2 of4 Sheet MAM/ER.

May 6, 1969 Filed Jan. 15, 1968 May 6, 1969 HTANNER 3,442,243

APPARATUS FOR SHIP STABILIZATION Filed Jan. 15, 1968 Sheet 4 of 4 AUnited States Patent Int. Cl: B63b 39/04 US. Cl. 114124 1 Claim ABSTRACTOF THE DISCLOSURE A member rotatable about the longitudinal axis of aship or other floating body is driven in alternate directions asrequired for the purpose of reducing roll. This member may comprise achain. A regenerative drive means is connected to the chain means and isselectively workable as a pump for transferring hydraulic liquid from asump means to a reservoir and as a motor driven by the hydraulic liquidto the sump means.

This invention relates to improved apparatus for ship stabilization.

The present invention is directed to apparatus for stabilizing the rollof a ships hull comprising guide means arranged in an athward shipsdirection around the ships hull, chain means extending around the guidemeans, reservoir means for containing hydraulic fluid under pressure,hydraulic liquid sump means, regenerative drive means operably connectedto the chain means and selectively workable as a pump for transferringhydraulic liquid from the sump means to the reservoir means and as amotor driven by the hydraulic liquid passing from the reservoir means tothe sump means, and roll sensing means responsive to rolling motion ofthe ship and operably controlling the functioning of the drive means asa motor and as a pump for damping motion of the ship by the reaction ofdrive imparted to the chain means.

An embodiment of the present invention will now be described, by way ofexample, with reference to the accompanying drawings.

FIGURE 1 diagrammatically illustrates apparatus for stabilizing the rollof a ship;

'FIGURE 2 is a diagrammatic cross-section of a ship showing a rollerchain type of stabilizing installation;

FIGURE 3 is a diagrammatic cross-section of a similar installation inwhich the roller chain extends over deck superstructure;

FIGURE 4 is an elevation of a suitable type of roller chain;

FIGURE 5 is an end view of the roller chain.

Referring now to FIGURE 1 of the drawings, the apparatus for shipstabilization consists of a wheel '10 mounted on an axis parallel to thecenterline of a ship and driven by a variable output pump/ motor 11 inseries with a sump 12 and a hydraulic accumulator 13. Associated withthe pump/motor '11 is roll sensing apparatus 14, which may be entirelyconventional, which determines the sign and magnitude of the pump/motortorque such that it is proportional to the angle of heel of the ship, orone or more of its derivatives and acts to counteract the roll.

To allow for losses either frictional or in the hydraulic system,practical apparatus would include a make-up pump, though this is notillustrated in the drawings.

When the apparatus is in use and the ship begins to roll to, say,starboard, hydraulic fluid passes from the 3,442,243 Patented May 6,1969 accumulator 13 through the pump/motor 11 to the sump 12. The torquedeveloped by the pump/motor 11, which is of course motoring, isproportional to the angle of roll and accelerates the wheel '10 in sucha direction that the reaction tends to roll the ship to port. As theship rolls back, the motor torque 11 decreases and when the ship rollsto port, the motor/pump 11 is driven by the wheel as a pump, with thetorque again being proportional to the angle of heel. In this way theroll of the ship is damped out to a very considerable extent, and thefluid drawn from the accumulator 13 in one quarter roll is pumped backfrom the sump 12 in the ensuing quarter roll thus making the hydraulicsystem regenerative. The component 10 has been referred to herein as awheel but it need not be a rigid element and may, for example, be madeof heavy roller chain 10a as shown in FIGURES 2-5.

Thus the chain 10a may be extended around the hull 14 of the ship, asshown in FIGURE 2, over rolls 15 and driven by a driving wheel 16,located over the keel 17, which in turn is driven by a belt or chaindrive '18 from the hydraulic pump/motor drive 1.

Alternatively, as shown in FIGURE 3, the drive may be extended over decksuperstructure by additional rollers 15a by way of a wheel house 19. Theincrease in hydraulic radius of the chain in the above-deck installationresults in the use of a lighter chain and lower powers.

Standard chains may be used: here a coice has had to be made on thepitch and number of rows. For instance, the three 2.5 in. triplex chainson the underdeck installation for a IOO-ton fishing vessel could bereplaced by a single 2 in. decaplex, which would give the same weightper foot run. The three triplex chains were chosen for ease ofinstallation.

One suggestion for a possible non-standard chain is shown in FIGURES 4and 5: if a large number of installations were considered, it might verywell be better economics to use such a design, which employs only onenon-standard part. This will affect the design of the stabilizer sinceboth the installations shown have been sized for minimum cost, which canbe shown to occur when the price of the chain and its associated bits isequal to the price of the drive. If the chain becomes cheaper, then theminimum first cost installations will have a heavier chain and lesspowerful drive.

I claim:

'1. An apparatus for stabilizing the roll of a ships l1ull, comprisingguide means arranged in an athwart ship direction around the ships hull,chain means extending around said guide means, reservoir means forcontaining hydraulic liquid under pressure, hydraulic liquid sump means,regenerative drive means operably connected to said chain means andselectively workable as a pump for transferring hydraulic liquid fromsaid sump means to said reservoir means and as a motor driven byhydraulic liquid passing from said reservoir means to said sump means,and roll sensing means responsive to rolling motion of the ship andoperably controlling the functioning of said drive means as a motor andas a pump for damping rolling motion of the ship by the reaction ofdrive imparted to said chain means.

References Cited UNITED STATES PATENTS 2,857,1-2-2 10/1958 Maguire244-93 3,252,426 5/1966 Parr 103-162 TRYGVE M. BLlX, Primary Examiner.

